SEOUL (REUTERS) - South Korean President Moon Jae-in tapped a seasoned former diplomat as his new ambassador to Washington on Friday (Aug 9) as Seoul steps up efforts to connect with the Trump administration on issues such as North Korea, defence costs and trade.

Mr Lee Soo-hyuck, a veteran diplomat who was South Korea's chief negotiator at six-party disarmament talks between 2003 and 2005, is a former deputy foreign minister and first deputy director of the National Intelligence Service.

Mr Lee, 70, represents a more conventional choice after Mr Moon first offered the position to Mr Moon Chung-in, the president's special adviser on foreign affairs and national security, South Korean newspaper JoongAng Ilbo and media reported on Friday.

Mr Moon Chung-in, a frequent political commentator whose positions were often seen to reflect the administration's thinking, declined the post, media reported.

A senior Blue House official said Mr Lee and Moon Mr Chung-in were considered for the post at the same time, and Mr Moon Chung-in did decline the post.

Mr Lee, who also served as South Korea's ambassador to Germany in 2005, was recruited to Mr Moon's team in 2016 ahead of his campaign for president and is currently a lawmaker in the ruling party.

The post is crucial to US and South Korean relations as the allies face North Korea's frequent missile launches amid stalled denuclearisation talks and US-South Korea military exercises.

US President Donald Trump said on Wednesday discussions had begun to get South Korea to pay more for the cost of maintaining US troops in the region to guard against any threat from North Korea.

South Korea has also tried to engage with US officials over its trade row with Japan.